Gas turbine

ABSTRACT

A gas turbine of the type having a plurality of axial compressor stages. The entire unit is mounted in a tubular support including coaxially mounted compressor and turbine blades for rotation independent of one another. The compressor blades are mounted in a ring radially inwardly of the ring of turbine blades, a combustion chamber is disposed radially inwardly of the ring of combustion ring. The gas first flow through the ring of compressor blades and then through the ring of turbine blades.

[ June 25, 1974 GAS TURBINE [76] Inventor: Eugeniusz Michael Rylewski, 43 Avenue du General Leclerc, 78 Saint-Remy-Les-Chevreuses, France [22] Filed: Aug. 2, 1971 [21] Appl. No.: 168,112

[52] US. Cl. 60/39.l6 C, 60/39.36, 60/39.66, 60/268, 415/79, 417/393, 417/408 [51] Int. Cl F02c 3/10, F020 7/16 [58] Field of Search 60/39.l6 C, 39.16 R, 268, 60/39.36; 415/79; 416/96, 97; 417/392, 393,

[56] References Cited UNITED STATES PATENTS 1,960,810 5/1934 Gordon ..60/39.l6C 2,428,330 9/1947 Heppner ..60/39.l6C 2,429,681 10/1947 Griffith 2,441,488 5/1948 Howell 2,548,975 4/1951 Hawthorne ..60/268 S l I T1 T2 T3 13 11 c1 c2 c3 R1 R2 R3 22in s 2,679,725 6/1954 Sharma 60/39.36 2,999,631 9/1961 Wollershauser 415/79 3,186,166 6/1965 Grieb 415/79 3,302,924 2/1967 Castle 416/96 Primary Examiner-Carlton R. Croyle Assistant Examiner-Robert E. Garrett Attorney, Agent, or Firm-Hane, Baxley & Spiecens [5 7] ABSTRACT A gas turbine of the type having a plurality of axial compressor stages. The entire unit is mounted in a tubular support including coaxially mounted compressor and turbine blades for rotation independent of one another. The compressor blades are mounted in a ring radially inwardly of the ring of turbine blades, a combustion chamber is disposed radially inwardly of the ring of combustion ring. The gas first flow through the ring of compressor blades and then through the ring of turbine blades.

6 Claims, 6 Drawing Figures PATENTEDJUNZSW 3.818.695

' sum 2 or 4 62 v I I a l 2 L 61 v v INVENTOR [usnwusz Mmnm. KvLnusm 1 GAS TURBINE The present invention relates to gas turbines. Gas turbines comprise a compressor in which the fluid is compressed, a chamber in which the temperature of the fluid is increased, usually at constant pressure, and the turbine per se in which the fluid is expanded.

The invention relates particularly to turbines having an axial type compressor. In such a compressor, a relatively large number of stages, twenty or more, have to be provided to obtain a large increasure in pressure with at an acceptable efficiency. These stages are mounted on one, two or even three shafts. Not only does the overall efficiency decrease with increasing number of stages, but its operating characteristics are not very satisfactory outside the speed range for which the compressor has been designed. Moreover, the fluid velocities in the subsequent stages are imposed by the preceding stages, so that it is difficult to avoid the stages in which the velocity of the fluid is supersonic. Such stages, at the present time, are less efficient than the subsonic stages. The majority of current gas turbines thus comprise a compressor unit with numerous rotors and stators, and a turbine unit also comprising a plurality of rotors and stators. These two units are divided by one or more combustion chambers.

Thus, gas turbines are relatively voluminous and heavy and especially not very versatile in their operation despite a considerable amount of research work which has been carried out to reduce their weight and overall dimensions, as well as to increase their range of operation. Moreover, the high temperature of the combustion gases at the inlet to the turbine unit, desirable for the overall efficiency of the cycle, creates a construction problem for the blades driven by the gases. Up to now, no really satisfactory solution has been found to this problem despite the different cooling arrangements which have been proposed.

The gas turbine, according to the present invention, eliminates these drawbacks. The invention consists in a series or turbine wheels, each turbine wheel including a ring of compressor blades and a ring of turbine blades, the wheels being mounted one after the other, and their rotation being independent with respect to one another. The gas flow pattern in such a turbine is such that the gases first pass through the rings of compressor blades and then through the rings of turbine blades.

The mechanical independence of successive wheels gives more freedom in the design regarding the solution for the circulation of the fluid. Accordingly all the rings of compressor blades can be subsonic, thus of a higher efficiency than supersonic wheels, while having a high pressure ratio owing to the different rotational speeds of the rings of compressor blades, the speed of each ring being adapted to the conditions prevailing therein. As the various wheels are mechanically independent, their rotational speed adjusts themselves automatically when running conditions change which provides an extremely versatile machine able to function efficiently within a wide range of operation.

Owing to the mechanical independence of the different wheels, the starting of the turbine is greatly simplified since, as a rule, it is sufiicient to set a single wheel in motion which may be done with a starter of reduced power.

In case gas lubricated bearings are used, the starter may send the quantity of fluid necessary for the fimctioning of these bearings, if only for the starting; during operation, the gas lubricated bearings may be supplied by the fluid from the compressor unit, or from the starter or from both the compressor unit and the starter.

In the embodiment according to the invention, the successive wheels rotate in directions opposite to one another. This eliminates the necessity of stator vanes between the wheels and considerably lightens the construction. Furthermore, the various wheels (except possibly those at the inlet and at the outlet) are of the reaction type having flat efficiency curves which further increases the operating efficiency under operation conditions, other than those for which the machine was designed.

According to a preferred embodiment, the wheels, mechanically independent of one another, each have a peripheral ring of blades allocated to the compressor unit. On account of the fact that the turbine unit is peripherally arranged, the efforts exerted upon it are relatively small which minimized the influence of the high temperature. Moreover, the proximity of the cold portion constituted by the compressor unit is favorable to the cooling of the turbine unit.

Advantageously, this cooling is ensured by the circulation of a fluid inside the hollow blades of the turbine and compressor units which communicate with each other, so that each wheel constitutes at the same time a heat exchanger allowing to maintain the blade temperature of the turbine unit at a level compatible with the characteristics of construction materials presently available.

Thus the provision of the rings of the turbine and compressor blades on one wheel not only allows higher gas temperatures in the first turbine rings, but also enables heat transfer between the rings of the successive wheels which lowers the temperature of the fluid leaving the turbine unit and increases the temperature of the fluid at the outlet of the compressor unit before it enters the combustion chamber. All these factors contribute to improve the thermal efficiency of the cycle.

The heat transfer between the turbine and compressor units enables the elimination of de-icing systems and the reduction of the weight of the system in the majority of cases.

Owing to the independence of the wheels and the flow of fluid in the same direction across the turbine and compressor units, the axial thrust on each wheel is reduced to a minimum, thr thrust corresponding to the turbine unit being cancelled out from the thrust corresponding to the compressor unit.

The turbine according to the invention preferably uses gas-lubricated bearings, but other bearings may be employed such as sliding bearings, rolling bearings and the like, as well as combinations thereof.

In a particularly compact alternative embodiment, the space within the wheels or blade rings is used to house the combustion chamber. The central space which is surrounded by the axial flow wheels is thus without inconveniency despite its relatively large diameter when a large amount of energy is to be transformed without excessively increasing the rotational speed of the wheels.

The tubular support for the wheels can therefore advantageously receive the combustion chamber, its construction being substantially simplified and reduced in weight.

The entire arrangement has an overall length substantially equal to that of the compressor stages of a standard gas turbine which is much less than that of the gas turbines generally in use.

The gas turbine, according to the invention, may work in open circuit, i.e. it comprises a combustion chamber in which the fluid, after being compressed, takes part in the combustion of the fuel. It may also work in closed circuit, the temperature of the compressed fluid being increased in a heat exchanger. The fluid, after its expansion in the turbine, can be returned to the compressor to start a new cycle.

The following description, made by way of example, refers to the accompanying drawings, in which:

FIG. 1 is a schematic view in cross-section of an embodiment of the gas turbine according to the invention;

FIG. 2 is a schematic view in perspective of a portion of a wheel;

FIG. 3 is a view of a portion of the turbine according to an alternative embodiment;

FIG. 4 is a schematic view of a turbine in crosssection according to another alternative embodiment;

FIG. 5 is a corresponding end view;

FIG. 6 is a schematic view according to further alternative embodiment.

Referring first to FIGS. 1 and 2, the turbine includes a tubular support 10 on which are mounted by means of bearings P P P,,, a certain number of wheels R R R disposed next to one another, enclosed in a stator 5. Each wheel R includes a root ring C with blades 11 and a peripheral ring T with blades 12. The blades 11 of the root ring C may have a different profile from those of the blades 12 of the ring T in a given wheel.

The heights of the rings C decrease from the ring C to the ring C and the heights of the rings T increase from the ring T to the ring T The ring C directly faces the ring C the ring C directly faces the ring C etc. Similarly, the ring T directly faces the ring T, and the ring T directly faces the ring T etc.

Sealing means 9 are provided between the wheels R, and R to avoid the flow of the gas from a compressor ring to a turbine ring or vice versa. Sealing means are also provided between the wheels R and the stator 5.

The blades 11 are mounted between an inner shroud 8 and an intermediate shroud 7 (FIG. 2), and the blades 12 are mounted between an intermediate shroud 7 and an outer shroud 6. In an alternative embodiment, the outer shroud may be omitted. A set of fixed vanes 4 is disposed between the ring C and the air inlet orifice 13. A deflector 14 positioned in front of the ring C directs the fluid flow leaving the ring towards the inlet 15 of the combustion chamber 16 having an inner line 17 housed inside the tubular support 10. The fuel injection system 18 and an ignition system are disposed in the vicinity of the inlet 15 of the chamber 16. An annular space is provided between the inner liner 1? and the tubular support 10. The liner 17 has passages 20. The outlet of the combustion chamber 16 is provided by manifold 21 which opens into a collector 22 whose outlet faces the peripheral ring T The pressure of the air or other fluid admitted through the intake 13 is increased by the first ring of blades C which delivers the fluid to the second ring C etc. the rings acting as the successive stages of a compressor. The air leaving the last ring C,, at high speed and pressure flows through the inlet 15 into the combustion chamber 16. The combustion of the fuel injected by the system 18 takes place in the chamber 16 and the high temperature combustion gases are conveyed by the manifold 21 to the collector 22 facing the peripheral ring T The gases, after having put the ring T into rotation by the turbine effect, leave the ring T and enter the ring T etc. until the ring T,,, rings T to T acting as the successive stages of a multistage turbine.

The blades of the wheels R are advantageously arranged so that wheel R rotates in a direction opposite to that of the wheel R the wheel R rotates in the same direction as the wheel R etc.

The gas flow leaving from the peripheral ring T may serve for the reaction propulsion for the vehicle on which the turbine is mounted.

It may also serve to drive a free-power turbine wheel 25 mounted on the power output shaft 26, as shown in dotted lines in FIG. 1.

Part of the air delivered by the last compressor stage C,,, instead of being introduced into the combustion chamber 16, is used to cool the inner liner 17 of the chamber by circulating in the annular space 19. A fraction of this air passes into the chamber 16 through the passages 20 provided in the liner 17. It may be used to feed the gas lubricated bearings.

In an embodiment according to the invention a blade 11 of the ring C and a blade 12 of the peripheral ring T of the same wheel R are hollow i.e. provided with an interior compartment 27 and 28 respectively (FIG. 2), the compartments being in communication with one another.

In a further embodiment, the shroud 7 is hollow and communicates with the compartments of the blades mounted thereon. A cooling fluid for example sodium is stored in the compartments 27 and 28 and possibly in the hollow shroud. Since the turbine blade 12 is at a higher temperature than the compressor blade, the temperature of the sodium in the compartment 28 therefore increases and its density decreases which in turn reduces the centrifugal force, so that the sodium tends to return to the compartment 27 where it cools down because of the lower temperature of blade 11. After cooling down by the increased effect of centrifugal force, the fluid reaches compartment 28. A circulation of cooling fluid is thereby effected which is favorable to the cooling of turbine blade 12.

The blades may be arranged as heating pipes.

The axial thrust exerted upon each wheel is relatively small because the wheel comprises a turbine ring and a compressor ring, the fluid flowing in the same direction across the turbine ring and in the compressor ring. A wheel R is mounted on the support 10 and a hydrostatic, hydrodynamic or combined gas lubricated bearing P is used.

In another embodiment of the turbine, each wheel R comprises not only a compressor ring C and a turbine ring T, but also a peripheral fan ring S, as shown in dotted lines in FIG. 1.

In the embodiment shown in FIG. 3, an inner casing 31 is provided between the inner liner 17 of the combustion chamber 16 and the support 10 for the wheels R. The air flow coming out of the compressor is circulated in the space 32 between the inner casing 31 and the tubular support which aids the cooling of the casing and possibly the operation of the gas lubricated bearings P.

Referring now to FIGS. 4 and 5, an embodiment is shown in which the combustion chamber 40 is disposed beyond the wheels R. The fuel intake is located at the end 41 of the chamber opposite to the end 42 adjacent to the wheels R. The air flow under pressure by means of the compressor rings of blades C, reaches the end 41 after circulating in an annular space 43 disposed between an inner liner 44 of the combustion chamber 40 and an outer casing 45. The air circulation inside the space 43 aids the cooling of the inner liner 44. Passages 46 are provided in the liner 44 for a second air flow.

Combustion gases leave the chamber through manifold 47 which winds round the wheels R and open into the collector 48 which in turn opens into a ring of stator vanes 49 positioned in front of a turbine ring 51, the ring of stator vanes being integral with a wheel 52 which is followed by a set of stator vanes 50. The stator vanes precede the wheel R The wheel 52 is integral with the shaft 53, this shaft acting as the force output shaft, the wheel 52 being positioned in front of the combustion chamber with respect to the body of the wheel R. The stator 50 may act as a bearing for the shaft 53. After passing through the peripheral turbine ring .51 and the stator 50, the combustion gases reach the peripheral ring T of the wheel R, etc. The combustion gases delivered by the turbine T of the last wheel R may provide a jet propulsion for the vehicle on which the arrangement is mounted. Gases are exhausted at the end opposite that which is adjacent to the shaft 53.

The turbine 51 is the first element by which combustion gases pass which is favorable to its use as freepower turbine. Moreover, it advantageously includes a compressor stage 56.

The turbine 51 has the slowest rotational speed of all the turbines of the machine which enables the use of a speed reducing mechanism of simple construction between the shaft 53 and a propeller.

According to an even further embodiment of the invention, two turbines are arranged to drive two coaxial propellers at the front of the machine.

In the embodiment shown in FIG. 6, the gases leaving the compressor stages C C flow through manifold 61 which returns them to the inlet of the machine where they enter an annular combustion chamber 62. Combustion gases are led to the first peripheral turbine ring under the same conditions as in the preceding embodiment via a stator. In this embodiment, there is not a turbine ring on each wheel. In the example, the first wheel includes a compressor ring C a turbine ring T and a second compressor ring C The rings C and C are separated by a stator. The second wheel includes two compressor rings C and C separated by a stator and a turbine ring T which is separated from the ring T by a stator. Such an arrangement may also be provided in the above-described embodiments.

I claim:

1. A rotating machine driven by fluid comprising a housing defining an envelope of revolution opened at first and second ends, a multiplicity of contiguous coaxial rotor wheels within said envelope, supporting means for rotatively supporting each wheel, each wheel comprising a first series of annular blades and a second series of peripheral blades, the heights of the blades of the first series progressively decreasing from one wheel to the next along a direction extending from said first end to said second end of the envelope, and the second series of blades of the wheels being of a progressively increasing height from one wheel to the next relative to the same direction, and guiding means for guiding the fluid that passes through the first series of blades of the wheels along said direction from said first end to said second end in order to direct it to face the second series of blades of the wheel at said first end, said guiding means comprising a combustion chamber fixed and housed within said supporting means.

2. A rotating machine according to claim 1, wherein the blades of the first series and the blades of the second series of a rotor wheel are hollow, and further comprising means for providing a fluid connection between the inside of a blade of the first series with the inside of a blade of the second series.

3. A rotating machine according to claim 1, wherein a rotor wheel comprises in addition to a first series of blades adjacent supporting means and a second series of blades, a third series of peripheral blades.

4. A rotating machine according to claim 1, wherein the blades of the first series are compressor blades and the blades of the second series are turbine blades, and one wheel supports two series of compressor blades and one series of turbine blades.

5. A rotating machine according to claim 1 wherein each of the wheels is supported by a gas bearing.

6. A rotating machine according to claim 1 wherein each of the wheels is supported by a hydrostatic bearmg' :4 

1. A rotating machine driven by fluid comprising a housing defining an envelope of revolution opened at first and second ends, a multiplicity of contiguous coaxial rotor wheels within said envelope, supporting means for rotatively supporting each wheel, each wheel comprising a first series of annular blades and a second series of peripheral blades, the heights of the blades of the first series progressively decreasing from one wheel to the next along a direction extending from said first end to said second end of the envelope, and the second series of blades of the wheels being of a progressively increasing height from one wheel to the next relative to the same direction, and guiding means for guiding the fluid that passes through the first series of blades of the wheels along said direction from said first end to said second end in order to direct it to face the second series of blades of the wheel at said first end, said guiding means comprising a combustion chamber fixed and housed within said supporting means.
 2. A rotating machine according to claim 1, wherein the blades of the first series and the blades of the second series of a rotor wheel are hollow, and further comprising means for providing a fluid connection between the inside of a blade of the first series with the inside of a blade of the second series.
 3. A rotating machine according to claim 1, wherein a rotor wheel comprises in addition to a first series of blades adjacent supporting means and a second series of blades, a third series of peripheral blades.
 4. A rotating machine according to claim 1, wherein the blades of the first series are compressor blades and the blades of the second series are turbine blades, and one wheel supports two series of compressor blades and one series of turbine blades.
 5. A rotating machine according to claim 1 wherein each of the wheels is supported by a gas bearing.
 6. A rotating machine according to claim 1 wherein each of the wheels is supported by a hydrostatic bearing. 